KR102469632B1 - Hydraulically treated nonwoven fabric and its manufacturing method - Google Patents

Abstract

Non-woven laminates having an SMS structure are hydraulically treated according to specific process parameters to improve flexibility and tactile feel. The nonwoven laminate may also be imparted with one or more regular holes by an additional hydro-treatment process, wherein the initial hydro-treatment provides improved hole definition.

Description

Hydraulically treated nonwoven fabric and its manufacturing method

The present invention relates to hydraulically treated nonwoven fabrics and improved methods of making hydraulically treated nonwoven fabrics.

Continuous improvement of hydraulically treated nonwoven fabrics is of interest in personal care products (eg, baby diapers, feminine hygiene, adult products) for both functional and perceptual reasons. In particular, abrasion resistance and flexibility are properties of interest. However, improvements that provide wear resistance generally reduce flexibility, and improvements that enhance flexibility generally reduce wear resistance. Therefore, a nonwoven fabric combining both abrasion resistance and flexibility is required.

Summary of the Invention

The present invention relates to an improved method for treating and forming pores in spunmelt nonwovens using high pressure water jets. Hydraulically treated or perforated nonwoven fabrics can be used, for example, in disposable absorbent products such as disposable diapers, incontinence and feminine hygiene products, and in medical and other industrial disposable products.

In an exemplary embodiment, the composite nonwoven fabric includes at least first and second nonwoven webs made from spunbond fibers; and a third nonwoven web made from meltblown fibers positioned between the first and second webs and thermally bonded to the first and second webs, wherein the composite nonwoven fabric is hydraulically treated; , the composite nonwoven fabric has a high level of abrasion resistance and flexibility.

In an exemplary embodiment, the nonwoven laminate includes a first nonwoven web substantially comprising meltblown fibers and a second nonwoven web comprising substantially spunbond fibers, wherein the nonwoven laminate has a regular bond pattern and a regular bond pattern. It has a hole pattern, wherein the holes of the regular hole pattern have an average diameter of 500 - 5000 microns.

In an exemplary embodiment, the nonwoven laminate further comprises a regular bond pattern having a bond area percentage greater than or equal to 10%.

In at least one embodiment, the nonwoven laminate is hydroengorged.

In an exemplary embodiment, the nonwoven laminate further comprises a regular hole pattern having a hole area percentage greater than or equal to 25%, and the ratio of the bond area percentage to the hole area percentage is 1:2.

In an exemplary embodiment, the nonwoven laminate comprises a first nonwoven web substantially comprising meltblown fibers and a second nonwoven web comprising substantially spunbond fibers, wherein the nonwoven laminate is hydraulically treated; is perforated in a regular hole pattern, and the nonwoven laminate has an abrasion rating of 3.0 or greater.

In an exemplary embodiment, a method of making nonwoven fibers includes bonding one or more webs substantially comprising spunbond fibers to a web comprising substantially meltblown fibers, wherein the bonding has a bonding area percentage greater than or equal to 15%. contain regular binding patterns; and a step of hydraulically treating the combined webs by a plurality of water spraying steps on a corresponding screen each having a predetermined pattern, wherein the water spraying step: the first pressure treatment of the combined webs at about 80-160 bar. a first water injection step of exposing to a plurality of water jets in a pressure range; a second water spray step of exposing the combined webs to a plurality of water jets at a second pressure range of about 80-160 bar; and a third water jetting step of exposing the combined webs to a plurality of water jets at a third pressure range of about 80-160 bar, the first water jetting step exposing a subset of the plurality of water jets to 80 bar. and holding at a bar, wherein the bonded webs comprise about 5% by weight of meltblown fibers.

In an exemplary embodiment, a method for producing a nonwoven fabric is calendered at a pressure of 90 N/mm between the embossed roll and the smooth roll at 152° C. and the smooth roll at 152° C. The step of performing the combining is further included.

In at least one embodiment, the first hole pattern is anisotropic.

In at least one embodiment, the nonwoven laminate includes a second hole pattern.

In at least one implementation, the second pattern is registered to the first pattern.

In at least one embodiment, the first polymer component is polypropylene.

In at least one embodiment, the first polymer component is viscose.

In at least one embodiment, the continuous fibers of the first layer include a second polymeric component.

In at least one embodiment, the second polymer component is polyethylene.

In at least one embodiment, the continuous fibers of the first layer are bi-component fibers.

In at least one embodiment, the nonwoven web has a basis weight within the range of 5 to 60 gsm.

In at least one embodiment, meltblown fibers comprise 2 to 35% of the total weight of the web.

In at least one embodiment, the nonwoven laminate further comprises a third layer comprising a nonwoven web comprising continuous fibers comprising a first polymer component, said third layer being hydraulically imparted with one or more aperture patterns. do.

According to an exemplary embodiment of the present invention, a method of making an apertured nonwoven web includes: forming a first nonwoven web comprising continuous spunbond fibers; forming a second nonwoven web comprising continuous meltblown fibers; combining the first and second nonwoven webs to form first and second layers, respectively; and hydraulically imparting one or more hole patterns in the first and second layers, from the second layer.

In at least one embodiment, forming the first nonwoven web includes a spunmelt process.

In at least one embodiment, the second web is a nonwoven web.

In at least one embodiment, forming the second nonwoven web includes a meltblown process.

In at least one embodiment, imparting the one or more hole patterns includes spraying water onto the combined layers on a drum having a first hole pattern.

In at least one embodiment, imparting the one or more hole patterns further comprises spraying water onto the combined layers on a drum having a second hole pattern.

In at least one implementation, the second pattern is registered to the first pattern.

According to an exemplary embodiment of the present invention, a method of making an apertured nonwoven laminate includes: forming a first nonwoven web comprising continuous spunbond fibers; forming a second nonwoven web comprising continuous meltblown fibers; forming a third nonwoven web comprising continuous spunbond fibers; calender bonding the first, second and third nonwoven webs at a pressure between 20 and 60 N/m (Newtons per meter) to form a laminate, wherein the bonding comprises a regular bonding pattern; and imparting one or more hole patterns by means of hydraulic pressure.

In at least one embodiment, the step of imparting the one or more hole patterns includes hydraulically treating the combined webs by a plurality of water spray steps on a corresponding screen, each having a predetermined pattern, and The spraying step includes: a first water spraying step of exposing the combined webs to a plurality of water jets at a first pressure range of about 80-160 bar; a second water spray step of exposing the combined webs to a plurality of water jets at a second pressure range of about 80-160 bar; and a third water jetting step of exposing the combined webs to a plurality of water jets at a third pressure range of about 80-160 bar, the first water jetting step exposing a subset of the plurality of water jets to 80 bar. and holding at a bar, wherein the laminate comprises about 5% by weight of meltblown fibers. In at least one embodiment, the one or more hole patterns are positioned such that at least a first hole formed in the nonwoven web by imparting a first hole pattern is at the same location as at least a second hole formed in the nonwoven web by imparting a second hole pattern. It is registered to be formed in .

In at least one embodiment, the first and second apertures are different sizes.

In at least one embodiment, the at least third holes formed in the nonwoven web by imparting the second hole pattern are formed at locations where there are no holes formed in the nonwoven web by imparting the first hole pattern.

In an exemplary embodiment, a nonwoven laminate includes first and second outer layers comprising spunbond fibers and a third inner nonwoven layer comprising meltblown fibers, wherein the nonwoven laminate has a bonding area of at least 10%. Bonded by rows in a regular bond pattern having a percentage, the nonwoven laminate includes a plurality of apertures arranged in a regular pattern.

In at least one embodiment, the average diameter of the holes in the hole pattern increases along the first direction.

In at least one embodiment, the frequency of holes in the hole pattern increases along the first direction.

In an exemplary embodiment, the nonwoven laminate includes first and second outer nonwoven layers comprising spunbond fibers; and a third inner nonwoven layer comprising meltblown fibers, wherein the nonwoven laminate is thermally bonded in a regular bond pattern having a bond area percentage of at least 10%, wherein the nonwoven laminate is subjected to a hydraulic treatment; The basis weight of the inner layer is at least 5 gsm (grams per square meter), and the nonwoven laminate has an abrasion rating of 4.0 or greater and an average Hand-O-Meter measurement (HOM) of 6.0 grams or less.

In at least one embodiment, the basis weight of the third inner layer is at least 10 gsm.

In at least one embodiment, the spunbond fibers of the first and second outer nonwoven layers comprise polypropylene and at least 5% by weight of a propylene-based elastomer, wherein the nonwoven laminate has an average Hand-O-Meter measurement of 6.0 grams or less. It has a value (HOM).

In at least one embodiment, the fibers of at least one of the nonwoven layers include a slip agent.

Other features and advantages of the present invention will become apparent from the following detailed description and accompanying drawings.

The present invention provides an improved method for treating and forming pores in spunmelt nonwovens using high pressure water jets. Hydraulically treated or perforated nonwoven fabrics can be used, for example, in disposable absorbent products such as disposable diapers, incontinence and feminine hygiene products, and in medical and other industrial disposable products.

The foregoing and related objects, features and advantages of the present invention will be more fully understood by reference to the following detailed description of preferred but exemplary embodiments of the present invention taken in conjunction with the accompanying drawings.
1 is a representative diagram of a system for hydraulically treating and perforating a nonwoven fabric according to a first exemplary embodiment of the present invention.
2A and 2B are representative diagrams of systems for hydraulically treating and/or perforating nonwovens according to second and third exemplary embodiments of the present invention, respectively.
3 is a table of selective results for hydraulically-treated nonwovens formed under process parameters and conditions, along with optional grades of nonwovens, according to an exemplary embodiment of the present invention.
4A, 4B and 4C are photomicrographs of nonwovens hydraulically treated under the process parameters and conditions illustrated in FIG. 3, according to an exemplary embodiment of the present invention.
5 is a table of selective results for hydraulically-perforated nonwovens formed under process parameters and conditions, along with optional grades of nonwovens, according to an exemplary embodiment of the present invention.
Figure 6 is a photomicrograph of a nonwoven fabric tested in comparison to the examples of Figures 4a-c.
7A, 7B and 7C are photomicrographs of hydraulically-punched nonwovens under the process parameters and conditions of FIG. 5, according to an exemplary embodiment of the present invention.
8 is a table of selective test results of hydraulically-treated nonwoven fabrics prepared according to an exemplary embodiment of the present invention compared to untreated nonwoven fabrics.

The present invention relates to improved techniques for hydraulically treating and perforating nonwoven fabrics and nonwoven fabrics made using such methods.

Hydraulically treated and/or hole patterned nonwoven webs according to the present invention are particularly suitable for use in disposable absorbent articles. As used herein, the term “absorbent product” means a product that absorbs and contains both fluid and solid materials. For example, an absorbent product may be placed on or proximate to the body to absorb and contain various exudates excreted by the body. Absorbent products are hygienic products used to absorb fluids and solid materials, such as worn products such as baby diapers, adult incontinence products, and feminine hygiene products, or professional medical personnel using products such as disposable gowns and chucks. can be In particular, the nonwoven fabric can be used as a body contact layer such as a top sheet or as part thereof. The nonwoven fabric may also be used for packaging or wrapping articles such as absorbent articles. The term “disposable” herein refers to an absorbent product that is not intended to be laundered or recovered or reused as an absorbent product, but is intended to be discarded after a single use, preferably recycled, composted, or disposed of in an environmentally sound manner. .

As used herein, the term "nonwoven fabric, sheet, layer or web" refers to a structure of individual fibers, filaments or threads arranged in a substantially random manner to form a planar material, as opposed to a knitted or woven fabric. Examples of nonwoven fabrics include meltblown webs, spunbond webs, carded webs, air-laid webs, wet-laid webs, and spunlaced webs. Nonwoven composite fabrics include two or more nonwoven layers.

As used herein, the term “spunbond fibers” means substantially continuous fibers or filaments having an average diameter in the range of 10-30 microns. Dividable bicomponent or multicomponent fibers having an average diameter in the range of 10-30 microns before splitting are also included.

As used herein, the term "meltblown fibers" means substantially continuous fibers or filaments having an average diameter of less than 10 microns.

Exemplary embodiments of the present invention may include varying the MB and/or SB fiber diameters to further improve the tactile feel of the material without compromising abrasion performance.

An exemplary embodiment of the present invention comprises a multi-layer composite fabric comprising at least one first layer fibers (preferably meltblown) bonded to at least one second layer fibers (preferably spunbond); , the median fiber diameter of the second layer fibers is at least 1.3 times greater than the median fiber diameter of the first layer. An exemplary nonwoven fabric may be formed in-line by sequentially depositing one or more layers of spunbond fibers followed by one or more layers of meltblown fibers onto a moving collecting surface. The assembled layers may be thermally bonded by passing them through a calender nip formed between two calender rolls. Each calender roll may or may not be heated. Each calender roll can be patterned or flat. Alternatively, the layers may be bonded ultrasonically, by adhesives, or through air bonding. In an alternative embodiment, the individual layers may be pre-formed and optionally combined and collected, such as by winding the fabric on a wind-up roll. The individual layers can then be assembled by laminating and joined together to form a composite fabric.

In embodiments, the base fabric can be an "SMS" structure that can be produced using single or multiple beams of both spunbond and meltblown, the fabric comprising an outer spunbond layer and an inner meltblown. have a loaf layer According to an embodiment of the present invention, the base fabric is pattern bonded by heat before being subjected to a hydraulic treatment. Without wishing to be bound by theory, it is believed that the thermal bonding holds the fibers relatively in place, limiting the movement of the fibers caused by the water jet. This also causes the meltblown fibers to degrade or deform while the integrity and thermal bonding of the spunbond layers remains relatively intact. The meltblown fibers thus degraded or deformed are entangled with the spunbond fibers, but the meltblown fibers are still thermally bonded to the base fabric as the thermal bond remains intact. Without wishing to be bound by theory, it is also believed that entanglement of the spunbond and meltblown fibers results in increased coiling of the spunbond fibers without significant degradation of the spunbond layer. It is also believed that the coiling behavior of spunbond fibers increases the loft of the material. In contrast to increasing entanglement, the hydraulic treatment used to increase loft in this manner is known as hydroengorgement. As used herein, the term hydroengagement is used to refer to a process in which hydraulic energy is applied to a nonwoven fabric resulting in an increase in flexibility and caliper mode compared to the nonwoven fabric prior to hydroengagement. Preferably, there is at least a 50% caliper increase. The hydroengagement process is described in detail in US Pat. No. 7,858,544, incorporated herein by reference. It is also believed that the MB fibers shift towards the outer surface, thereby improving the tactile feel of the material. Within the apertured fibers, the entanglement of the meltblown fibers improves the definition of the edge of the hole.

An embodiment of the present invention is shown in FIG. 1 . First, a nonwoven web (hereinafter also referred to as “fabric” or “base fabric”) 6 is formed on a conveyor belt using a spunbond beam 2, a meltblown beam 3, and a spunbond beam 4. (8) Form on top. Next, the web 6 is combined with the calender rolls 10 and 12. According to a further exemplary embodiment of the present invention, a plurality of elements corresponding to each beam 2, 3, 4 are introduced into the system to form a plurality of respective layers of the web 6, for example a plurality of of meltblown layers may be deposited to form a SMMS or SMMMS fabric. According to exemplary embodiments of the present invention, meltblown fibers may constitute between 2% and 35% of the total weight of the web 6 .

According to an exemplary embodiment of the present invention, the spunmelt nonwoven web consists of continuous filaments that are placed on a moving conveyor belt 8 in a random distribution. The resin pellets are melted under heating and then fed through a spinneret (or spinning beams 2 and 4) to form hundreds of filaments using a stretching device (not shown). As previously described, a plurality of spinnerets or beams (side-by-side blocks) may be used to provide increased densities of spunbond fibers corresponding to, for example, spin beams 2 and 4, respectively. . A jet of fluid (such as air) draws the fibers from beams 2 and 4, which are then blown or conveyed onto a moving web (conveyor belt) 8, where in a random pattern a suction box (not shown) is laid against the web 8 and drawn to form the fabric structure 6 . A meltblown layer is deposited by a meltblown mechanism (or "beam") (3) between the spunbond layers laid down by radiation beams (2) and (4). The meltblown (MB) layer may be meltblown, but may be formed by various other known processes. For example, the meltblowing process involves inserting a thermoplastic polymer into a die. The thermoplastic polymer material is extruded through a plurality of fine capillaries in a die to form fibers. The fibers flow into a high velocity gas (eg, air), which weakens the streams of molten thermoplastic polymer material and reduces their diameter to a diameter that may be a microfiber diameter. The meltblown fibers are deposited quasi-randomly by beam 3 onto a spunbond layer laid down by radiation beam 2 to form a meltblown web. Multiple dies may be placed side by side in a block to produce enough fibers across the full width of the nonwoven fabric 6, and two or more blocks may be used side by side to increase fiber coverage. The meltblown fibers may be tacky as deposited, which generally results in bonding between the meltblown fibers of the web.

In a preferred embodiment, the fibers used to form web 6 are thermoplastic polymers, such as polyolefins, polyesters (eg, polylactic acid or “PLA”), polyamides, copolymers thereof (olefins, esters) , with amides or other monomers) and blends thereof. As used herein, the term “blend” includes a homogeneous mixture of at least two polymers or a heterogeneous mixture of at least two physically distinct polymers, such as a two-component fiber. Preferably, the fibers are made from polyolefins, examples of which include polyethylene, polypropylene, for example, propylene-butylene copolymers and blends thereof, including ethylene/propylene copolymers and polyethylene/polypropylene blends. . Resins with higher crystallinity and lower elongation at break may also be suitable due to their more likely to break. Other formulation changes, such as the addition of CaCO ₃ , can be used to provide spunbond fibers that are easier to break and/or permanent set, and thus better punctured.

In an exemplary embodiment, web 6 may be thermally calendered via rollers 10 and 12 . Additionally, meltblown fibers (from beam 3) either during initial web formation or as a result of low pressure calendering due to the meltblown fibers staying at a temperature high enough to adhere to the spunbond fibers of beams 2 and 4. The degree of coupling can be given by One or both of the rollers 10 and 12 have a circumferential surface machined, etched, embossed or otherwise formed to have a pattern of protrusions and depressions thereon so that the bonding pressure exerted on the web 6 at the nip is It is concentrated on the outer surface and reduced or substantially eliminated in the recesses. According to an exemplary embodiment of the present invention, rollers 10 and 12 may be a calender 10 having bonding rolls 12 defining a bonding pattern. According to an exemplary embodiment of the present invention, the bonding pattern defined by bonding roll 12 may have a bonding area percentage greater than 10%. Commonly owned U.S. Patent Nos. 6,537,644 and 6,610,390, each incorporated herein by reference, disclose nonwoven fabrics having fusion bonds in a non-symmetric pattern (ie, an anisotropic or asymmetric pattern). The bonds are elongated in one direction and form (a) a closed figure oriented parallel to a unidirectional axis, (b) a closed figure oriented across an adjacent closed figure along a unidirectional axis, and (c) a closed figure oriented along a unidirectional axis. It may be a closed figure selected from the group consisting of close closed figures and oriented sets so as to be formed between closed structures extending along it. Alternatively, web 6 may be bonded via ultrasonic bonding or air bonding. The degree of bonding used may vary depending on the type of hydraulic treatment used. In an exemplary embodiment, a hydraulic treatment may be applied to the fully bonded SMS web 6, resulting in hydroengagement of the spunbond layers with the fibers of the meltblown layer becoming entangled with the spunbond fibers. For exemplary SMS webs made primarily of polypropylene fibers, a “well-bonded” pattern can be obtained using a bonding pressure of about 90 N/m and a temperature of about 150° C. Without wishing to be bound by theory, it is believed that the increased degree of bonding results in a more uniform spunbond layer, improving the appearance of the web 6. In another exemplary embodiment, the adhesive or mid-bonded SMS web 6 may be hydraulically treated to form apertures. The web 6 can also be hydroengorged before being perforated. It is believed that a more moderate degree of bonding prevents the bonding points from interfering with hole formation while still providing sufficient integrity for the fabric to have high abrasion resistance. For SMS webs made primarily from polypropylene, suitable bonding degrees can be obtained using bonding pressures in the range of 20 N/m to 60 N/m.

According to the present invention, the web 6 is then hydraulically treated using a plurality of water jet jets 16a, 16b and 16c, each element 16a, 16b and 16c illustrated in FIG. 2a respectively Multiple injector sets in a given arrangement may be represented. According to an exemplary embodiment of the present invention, web 6 is conveyed by conveyor 22 underneath sprayers 16a-c, and high pressure water jets act upon and pass through the fabric. Corresponding water sinks, or vacuum lights 20a, 20b and 20c, may be placed below the location of each sprayer (set) 16a-c to draw in water and dry the fabric 6. The nonwoven web 6 may then be dried by blowing hot air through the fibrous web, by an IR dryer, or by other drying techniques (eg, air drying).

According to an exemplary embodiment of the invention, conveyor 22 may include one or more screens, for example by using one or more drums 14 and a corresponding sleeve 18 acting as said one or more screens. , each having a predetermined pattern for supporting the fabric/web 6 during hydraulic treatment by the respective water jets 16a-16c. The screen(s) may include a hole pattern for perforating the fabric/web 6 . According to an embodiment of the present invention, no more than three sets of sprayers 16a-16c may be used to hydraulically treat and/or perforate the fabric/web 6. As described in more detail below with reference to FIGS. 3 and 4 , the water jets 16a - 16c may be set to respective water pressures.

According to an exemplary embodiment of the present invention, a pressure of about 80-200 bars may be used for hydraulic treatment and orifice.

2A and 2B illustrate an exemplary embodiment of the present invention using one or multiple drums for hydraulically treating and/or perforating an SMS or SM fabric. Like elements are denoted by the same reference numerals as those described in FIG. 1, and repeated descriptions of these elements are omitted.

As shown in FIG. 2A , a base fabric 6 may be formed on a conveyor belt 8 using spunbond beams 2 , meltblown beams 3 and spunbond beams 4 . The web 6 may then be combined with calender rolls 10 and 12 . Again, according to a further exemplary embodiment of the present invention, a plurality of elements corresponding to each beam 2, 3, 4 may be introduced into the system to form respective layers of a plurality of webs 6 - For example, a plurality of meltblown layers may be deposited to form an SMMS or SMMMS fabric. According to embodiments of the present invention, the substrate fabric/web 6 is then hydraulically treated by one or more water jet sprayers 16 . Next, holes may be hydraulically imparted to the nonwoven web 6 using one or more drums 14 and a plurality of water jets 16 having a pattern of holes. According to an exemplary embodiment of the present invention, the drum 14 may be covered with a sleeve 18, which sleeve may be made of metal or plastic having a predetermined pattern for supporting the fabric/web 6. . According to an exemplary embodiment of the present invention, the predetermined pattern may include a perforated pattern, and the perforated pattern may have a perforated area percentage of 25% or more. The average diameter of the pores may be on the order of 500 - 5000 microns. As the web 6 is wrapped around the drum 14 and passes under the sprayer 16, the high-pressure water jets act upon the fabric and pass through the fabric and onto the sleeve 18 according to a pattern. transform the fabric. A water sink or vacuum slot/area 20 is disposed below each injector 16 location to draw in water, or to remove water through holes, thereby forming the fabric 6 within the substrate fabric (web 6). Holes may be processed or formed in a pattern corresponding to that of the lower sleeve 18 . The nonwoven web 6 may then be dried by blowing hot air through the fibrous web, or by an IR dryer, or by other drying techniques (eg, air drying).

As shown in Fig. 2a, perforation is performed by providing at least one, preferably a plurality of water jet beams (jet 16) on one drum 14 so that subsequent drums do not interfere with the clarity of the perforation pattern. can be done Subsequent drums use a lower pressure water jet to help entangle any broken fibers and/or improve web integrity without redirecting or “washing” the fibers through the hole. can be characterized.

As shown in Figure 2b, via radiation beam 2 and assembly 3, an MB layer is deposited over the SB layer. Again, multiple blocks corresponding to elements 2 and 3 may be used for fiber coverage. A flat calender roll 10 can be used to bring the lower temperature MB layer into communication and direct contact with the higher temperature embossed calender roll 12 . As further shown in FIG. 2B, a plurality of drums 14a and 14b are used in communication with water injectors 16a and 16b, sleeves 18a and 18b, and water collectors 20a and 20b, A plurality of steps may be provided for treating or perforating the nonwoven web 6 . According to an exemplary embodiment of the present invention, the hole pattern on the sleeves 18a and 18b is formed on the drums 14a so that the perforation can be further improved in its geometric definition and 3D structure by using the second drum 14b. and 14b). That is, the register of the hole pattern on the sleeves 18a and 18b allows a hole formed on the first drum 14a to be placed directly over a corresponding hole on the second drum 14b. According to a further exemplary embodiment, more than one set of water injectors 16a and 16b may be used with a corresponding assembly to accommodate such additional sets of water injectors. In embodiments, the hole pattern may also be registered substantially exclusively, ie, such that the bond pattern has minimal overlap between bond and hole.

In embodiments, the hydraulic treatment may include no more than three water spray steps exposing the web 6 to a plurality of water jets at a pressure in the range of about 80-160 bar per second. In another implementation having three water injection stages, a subset of the water jets in the first injection stage may be maintained at about 80 bar per second.

In implementations, apertures of other properties may be formed. Specifically, the size and shape of the holes may vary. For example, holes of different sizes may be arranged in a regular pattern. In some applications where the visual properties of the nonwoven fabric differ from those of the layer beneath the nonwoven fabric, the apertures may be arranged to form gradients or other graphic elements such as figures or shapes. In embodiments, the properties of a perforated nonwoven fabric can vary as a result of the open area percentage, frequency and size of holes between different regions in the nonwoven fabric. Such a nonwoven fabric may be a perforated nonwoven fabric for use as a topsheet in a diaper in which the hole diameter increases from front to back to improve the transfer of solid materials. Alternatively, the frequency of holes can be increased along the length of the nonwoven laminate while keeping the hole diameter the same.

The substrate fabric 6 is subjected to about 100 cycles prior to being fed into a hydraulic treatment device comprising, among other elements, a conveyor 22 (and/or drum 14), a water jet 16, and a water collector 20. It is preferably preheated above Fahrenheit. Preheating of the web 6 may be done using a thermal calendering device (such as rollers 10 and 12), an infrared device, a hot air blower, or a combination thereof. Also, the water used in the hydraulic treatment device, i.e. the water from the injector 16, can be heated. Preheating of the web 6 makes the meltblown fibers more flexible, providing improved characteristics and better aperture definition at lower water jet pressures, and limiting fiber breakage.

In embodiments, one or both of the spunbond and meltblown layers have one or more in-melt hydrophilic additives added to any/all of the individual web layers. This hydrophilicity added to the base polymer web allows the individual PP filaments to absorb some water during the pre-entangling step of the hydroentanglement process. Increased water absorption imparts greater flexibility, providing better hole sharpness and minimal fiber breakage at lower water jet pressures.

In an exemplary embodiment, the spunbond fibers include additives to improve flexibility. Examples of such additives include random copolymers (eg, Total ^TM 7860 (Total SA), Moplen® RP348SK (Reg. No. 0711971, under license to PolyMirae from lyondellbasell), etc.); slip additives (eg, PolyVel® S-1519, S-2446 (Reg. No. 1423496 from PolyVel, Inc.)); and other flexibility additives (eg Techmer® RPM11790 (Reg. No. 3001764, from Techmer PM, LLC), Accurel® GA 300 (Reg. No. 1141925, from Armak Co.), or FW505, FW515 (Keimei Plastifizierung from Technik (Yantai) Co., Ltd.)). Additives such as those described above may also be added to MB fibers to modify surface feel and physical performance, such as wear rate. In an exemplary embodiment, the base fabric having the SMS structure is present in an amount of 2 to 30% of the total web weight, more preferably 3-15% of the total web weight, and most preferably about 5% of the total web weight. Contains meltblown fibers.

In an exemplary embodiment of the present invention, a second calendering step using, for example, rollers similar to elements 10 and 12 is used to provide additional thermal bonding to web 6 after the perforation process to improve web integrity. can reduce damage to and/or loose fibers. This step may be performed with a sealing heat treatment at 130 to 150° C. and a pressure in the range of 30-90 N/mm. Topical treatments can also be used to minimize loose fiber ends. Alternatively, bonding through air may be used to provide additional thermal bonding.

In an exemplary embodiment, the nonwoven web resulting from the process has a Bond Area Percentage (Bond Area) greater than 10%, preferably greater than 15%, more preferably in the range of 16-22%, and even more preferably in the range of 18-20%. area percentage). The “bond area percentage” on a nonwoven web is the ratio of the area occupied by bonding impressions to the total surface area of the web, expressed as a percentage and measured according to the Bond Area Percentage method described herein. A method for determining the percent binding area is described in US Pat. No. 8,841,507, incorporated herein by reference. The nonwoven web may also have a pore area percentage in the range of about 10-40%. Exemplary nonwoven webs have hole area to bond area ratios of from 3:1 to 1:1.

In implementations, the apertures of the nonwoven web can be characterized as being based on specific criteria. In an exemplary embodiment, the edges of the apertures may differ from the rest of the surface of the nonwoven web in one or more of opacity, reflectivity, or color. In an exemplary embodiment, the nonwoven web may be laminated onto a sheet such that the sheet surface is visible through apertures in the nonwoven web. The sheet may be a film, nonwoven fabric, fabric or composite. In an exemplary embodiment, the portion of the sheet visible through an aperture in the nonwoven web may differ from the edge of the aperture in one or more of opacity, reflectivity, or color. Furthermore, a gradient of one or more of opacity, reflectivity, or color may be formed by the surface of the nonwoven web, the perforated edges, and the portion of the sheet visible through the perforations of the nonwoven web.

The nonwoven web 6 may be incorporated into a nonwoven laminate. The nonwoven laminate may include additional layers of continuous fibers such as spunbond fibers and meltblown fibers, and may include composite nonwoven fabrics such as spunbond-meltblown-spunbond laminates. The nonwoven laminate may also contain short fibers such as staple fibers or may contain pulp fibers. The nonwoven laminate may also contain a superabsorbent material in particulate or fibrous form. The laminate may be formed through typical means including, but not limited to, thermal bonding, ultrasonic bonding, chemical bonding, adhesive bonding, and/or hydroentanglement. In accordance with embodiments of the present invention, web 6 may form a nonwoven laminate formed from one or more of the previously described processes for use as a topsheet, absorbent core, or backsheet of an absorbent article.

Examples of hydraulically treated nonwoven fabrics made according to exemplary embodiments of the present invention are included in the tables illustrated in FIGS. 3 and 5 . As shown therein, the samples are the base nonwoven fabric, the basis weight (BW) of the nonwoven fabric (gsm: grams per square meter), the transfer speed (mpm: meters per minute), the number of water jet sets used (C1, C2, and C3; For each water jet set, along with the strip structure, bra, and screen structure used), whether or not a dryer was used, and the corresponding description of the comparative grade for the visual abrasion resistance of the resulting sample, T# ( or Trial#). The materials used for the base nonwoven fabric in the process for the results shown in FIGS. 3 and 5 correspond to those shown in Table 1 together with the number identifiers, respectively.

substance 1 30 gsm SMS substance 2 30 gsm SMS substance 3 30 gsm SMS substance 4a 30 gsm SMS substance 4b 30 gsm SMS Substance 5 30 gsm SB

Material 1 was a 30 gsm SMS laminate in which polypropylene spunbond material was bonded with meltblown fibers (30% by weight) to form a 30 gsm (grams per square meter) SMS structure. Materials 2-4b had spunbond layers made from 25% Vistamaxx® 7020BF (Regstration Number 3074180, from Exxon Mobil Corporation) and 2500 ppm erucamide and polypropylene, and meltblown layers made from polypropylene. For Material 2, the laminate was 30 wt % meltblown fibers. For material 3, the laminate was 12 wt% meltblown fiber. For materials 4a and 4b, the laminates were 5 wt % meltblown fibers. Material 5 had a 35 gsm polypropylene spunbond fabric.

As shown in FIG. 3, bonding conditions (adhesive-bonding, intermediate bonding, and full-bonding) are further applied according to the following parameters for the materials used in each example corresponding to those listed in Table 1 above. indicate

Material 1 (Medium Bond): Embossed-Roll = 150°C, Flat-Roll = 150°C, Pressure = 60 N/mm

Material 2 (adhesive-bonded): embossed-roll = 145°C, flat-roll = 145°C, pressure = 30 N/mm

Material 3 (adhesive-bonded): embossed-roll = 145°C, flat-roll = 145°C, pressure = 30 N/mm

Material 4a (adhesive-bonded): embossed-roll = 145°C, flat-roll = 145°C, pressure = 30 N/mm

Material 4b (fully-bonded): embossed-roll = 152°C, flat-roll = 152°C, pressure = 90 N/mm

Also, as reflected in the table of FIG. 1, the strip and screen used with the water jet sets C1, C2 and C3 for hydraulically treating nonwovens are as follows:

Strip: 1R: Metal strip perforated with a row of very small holes across its width, from which high-pressure water flows to form water needles that impinge on the non-woven fabric and paper and entangle the fibers together.

Strips: 2R and 2Rb: A metal strip perforated with two rows of very small holes across its width, from which high-pressure water flows to form water needles that impinge on the non-woven fabric and paper and entangle the fibers together.

Screen - MSD: A metal sleeve that fits over a drum in a hydraulic jet-lacing device, to which a hydraulic water needle is applied to the material. 100 holes/cm2 with a 300 micron diameter. 8% open area.

Screen—AS1: A metal sleeve with a matrix of holes allowing patterning into the nonwoven fabric based on water flow through the screen—average hole size 1 mm x 0.5 mm. MD X CD.

Screen—AS2: A wire-mesh sleeve with a matrix of holes allowing patterning into the nonwoven fabric based on water flow through the screen—average hole size 0.9 mm x 1.5 mm. MD X CD.

Screen - AS3: Metallic sleeve with a matrix of holes allowing patterning into the nonwoven fabric based on water flow through the screen - average hole size 3 mm x 2 mm. MD X CD.

The results shown in FIG. 3 relate to the comfort touch parameters for the samples compared to the base nonwoven fabric used in each process. The parameters are resultant basis weight (BW), AP (air permeability) (cfm: square feet per minute), thickness, CDT (transverse tensile strength) (N/cm: Newtons per centimeter), MD HOM (longitudinal handle- O-Meter) (g), CD HOM (Width Handle-O-Meter), Avg HOM (Average Handle-O-Meter), Kinetic CoF (Coefficient of Friction), and "Visual Wear Resistance".

Handle-O-Meter (HOM) stiffness measurement of nonwoven fabric is performed by slightly modifying it according to the WSP test method 90.3dp. The quality of "hand" is considered a combination of resistance due to surface friction and flexural strength of the sheet material. The apparatus used in this test method is available from Thwing Albert Instrument Co. In this test method, a 100 x 100 mm sample was used for HOM measurement and the resulting final reading was reported "as is" in grams without doubling according to WSP test method 90.3DP. Mean HOM was obtained by averaging the MD and CD HOM values. Typically, the lower the HOM value, the higher the flexibility and stretch, while the higher the HOM value, the lower the flexibility and stretch of the nonwoven fabric.

Tensile strength measurements are performed according to the WSP method, more specifically WSP 110.4(05)B, using an Instron testing machine. Measurements are made in both the MD and CD directions, respectively. CD tensile strength (CDT) (N/cm: Newtons per centimeter) and elongation (CDE) (%) are reported in the results table in FIG. 3 .

Other reported properties, such as air permeability and thickness measurements, were determined according to ASTM or INDA standard test methods.

The "Abrasion Rating" resistance parameter relates to the NuMartindale Abrasion measurement of the abrasion resistance of a fabric sample surface and is performed according to ASTM D 4966-98, incorporated herein by reference. The NuMartindale Abrasion test was performed on each sample using a Martindale Abrasion and Pilling Tester by performing 40 to 80 abrasion cycles on each sample. Test results are reported after all wear cycles have been completed or the test sample has failed. Preferably, there should be no visible changes to the surface of the material.

For each sample, according to NuMartindale Abrasion, abrasion ratings were determined based on a visual rating scale of 1 to 5 with a scale defined as:

5 = Excellent = very few or no fibers removed from the structure.

4 = very good = low level of fibers that may be in the form of pills or small strings.

3 = Moderate = Medium level of fibers and large or multiple strings.

2 = Poor = High level of loose strings that can be easily removed.

1 = Very bad = Significant loss of structure, holes, large loose strings that can be easily removed.

As shown in Figure 3, tests 4b.9, 4b.10 and 4b.11 resulted in significant improvements in most parameters compared to their base nonwoven fabric (Material 4b in Table 1), with the most significant improvement in abrasion ratings. did As further shown in Figure 3, trials 4a.15, 4a.16, 3.9 and 3.10 also showed some improvement.

Example 1 (tests 4b.9, 4b.10 and 4b.11 in FIG. 3)

A nonwoven fabric having an SMS structure and a basis weight of 30 gsm (grams per square meter) was used (Material 4b in Table 1). The spunbond layers of the nonwoven fabric were made from a polypropylene blend comprising erucamide and a propylene-based elastomer. The meltblown layer constituted 5% of the total weight of the nonwoven fabric. A sample of the nonwoven fabric was hydraulically treated using three sets of hydraulic streams on an MSD screen at a transmission rate of 200 mpm.

For test 4b.9, 3 sets of injectors were each set to a pressure of 80 bar. For test 4b.10, three sets of injectors were demonstrated at a pressure of 120 bar each except for one 80 bar injector. For test 4b.11, three sets of injectors were set at a pressure of 160 bar each except for one 80 bar injector. The samples showed improved thickness (0.284-0.358 mm vs. 0.274), CDT, HOM (particularly MD HOM), and wear ratings. As reflected in Figure 3, all samples exhibited an Avg HOM of less than 6.0 g (5.1 g - 5.5 g) and a wear rating of 5. In trials 4b.10 and 4b.11, samples further showed improved AP.

4A, 4B and 4C are photomicrographs of hydraulically-treated nonwovens under process parameters and conditions reflected in FIG. 3, according to an exemplary embodiment of the present invention. In particular, Figures 4a, 4b and 4c are photomicrographs of the nonwovens from trials 4b.9, 4b.10 and 4b.11, respectively, identified and reflected in Figure 3. As shown in Figures 4a-c, nonwoven fabrics include particularly desirable fiber bonds and entanglements.

5 shows a table of results for samples, identified by Trial # (or T#), which exhibit a particularly positive hole feature, as reflected by a high relative rating for the hole feature. The table of FIG. 5 also illustrates additional characteristics of the resulting apertured nonwoven samples. As shown in FIG. 5 , samples of Material 5 were bonded at modified parameters related to “adhesive-bonding” previously defined—namely, 45 N/mm, and 130-150° C. Other samples were also prepared at bonding pressures ranging from 30 - 90 N/mm.

Corresponding to Fig. 5, Table 2 below shows the screens (Screen IDs) used in the water jetting process according to exemplary embodiments of the present invention having the corresponding orifice sizes.

screen ID Hole size, MD x CD, mm AS1 1 x 0.5 AS2 0.9 x 1.5 AS3 3x2

Example 2 (Test 2.4 in Fig. 5)

A nonwoven fabric having an SMS structure and a basis weight of 30 gsm (grams per square meter) was used, in particular, material 2 of Table 1 described above. The sample nonwoven fabric was hydraulically treated using two sets of hydraulic streams on the MSD screen at each pressure of 60 to 80 bar at a delivery rate of 50 mpm and a third set of hydraulic streams on the AS1 screen at 100 bar. The sample exhibited a good hole and wear rating of 4, an Avg HOM of less than 6.0 g (5.29 g).

Example 3 (Test 4a.9 in Fig. 5)

A nonwoven fabric having an SMS structure and a basis weight of 30 gsm (grams per square meter) was used, in particular Material 4a of Table 1 described above. The sample nonwoven fabric was hydraulically treated using two sets of hydraulic streams on the MSD screen and a third set of hydraulic streams on the AS2 screen at 150 bar at respective pressures of 60 to 80 bar at a delivery rate of 50 mpm. The sample exhibited a good hole and wear rating of 3, an Avg HOM of less than 6.0 g (5.19 g).

Example 4 (Test 3.7 in Fig. 5)

A nonwoven fabric having an SMS structure and a basis weight of 30 gsm (grams per square meter) was used, specifically Material 3 of Table 1 described above. The nonwoven sample was hydraulically treated using two sets of hydraulic streams on the MSD screen and a third set of hydraulic streams on the AS2 screen at 150 bar at each pressure of 60 to 80 bar at a delivery rate of 50 mpm. The sample showed an acceptable hole and wear rating of 3, an Avg HOM of less than 6.0 g (4.67 g).

6 is a photomicrograph of the nonwoven fabric tested compared to the exemplary nonwoven fabric from tests 4b.9, 4b.10 and 4b.11 of FIGS. 4a-c. As shown in Figure 6, the nonwoven fabric has poorer fiber bonding and entanglement compared to those shown in Figures 4a-c.

7A, 7B and 7C are photomicrographs of hydraulically-punched nonwovens under process parameters and conditions reflected in FIG. 5, according to an exemplary embodiment of the present invention. In particular, FIGS. 7A, 7B, and 7C illustrate representative samples of nonwovens hydraulically apertured with screens AS1, AS2, and AS3, respectively.

Example 5 (FIG. 8)

8 is a table of additional results for an example of a hydraulically-treated nonwoven fabric prepared in accordance with an exemplary embodiment of the present invention. 8 also includes results for a control sample using a base nonwoven fabric that has not been hydraulically treated. As shown in Figure 8, the base nonwoven fabric was 22 gsm SMS with 5% MB and fully-bonded (full-bonded as previously defined). In particular, "SMS" contained 15% Vistamaxx (7020BF) and 2000 ppm erucamide in a spunbond (SB) layer; “SMS 1” contained 5000 ppm erucamide in meltblown (MB) layers and 15% Vistamaxx®, 2000 ppm erucamide in SB layers; “SMS 2” contained 25% Vistamaxx®, 2000 ppm erucamide in SB layers. As shown in Figure 8, the first control sample was not water treated, and the other samples were subjected to four sets of 2Rb water jet strips (as previously defined) at respective pressures of 80-200 bar on MSD screens (as previously defined). as defined) was added.

8 is a nonwoven fabric basis weight (BW) (gsm: grams per square meter), sample thickness (mm), density (g / cc: grams per square centimeter), air permeability (AirPerm) (cfm), MD tensile strength, MD Elongation at Elongation, CD Tensile Strength, and CD Elongation at Elongation are shown.

The Handle-O-Meter (HOM) stiffness of the samples was measured according to the method described above, and all samples showed a desirable average HOM of 6.0 or less, as shown in FIG. 8 . All samples showed significantly improved average HOM (4.4 g vs. 2.7 - 3.3 g) and especially improved CD HOM (3.5 g vs. 1.0 - 1.7 g) compared to the untreated control sample. In addition, all samples exhibited a desirable visual abrasion of 4.0 - 5.0 on the previously described scale over 80 cycles, which is similar to or better than the untreated control sample. In addition, these samples were measured for opacity and showed a desirable opacity of greater than 40%, similar or improved (42.5% vs. 41.9% - 47.0%) than the untreated control sample. Opacity was measured according to INDA 60.1-92.

Although detailed descriptions of specific embodiments of the invention have been set forth in the foregoing specification, it will be understood by those skilled in the art that many of the details provided herein may be changed significantly without departing from the spirit and scope of the invention.

Claims (24)

first and second outer nonwoven layers comprising spun-bond fibers; and
Third inner nonwoven layer comprising meltblown fibers
As a non-woven laminate comprising,
the nonwoven laminate is thermally bonded in a regular bond pattern having a bond area percentage greater than or equal to 10%;
The non-woven laminate is hydraulically treated;
the basis weight of the third inner nonwoven layer is greater than or equal to 5 grams per square meter (gsm);
The nonwoven laminate has an abrasion rating of 4.0 or greater, and an average Hand-O-Meter Measurement (HOM) of 6.0 grams (g) or less, wherein the Hand-O-Meter Measurement (HOM) is determined according to Modified WSP Test Method 90.3 measured, and the average Handle-O-Meter is obtained by taking the average of MD (machine direction) and CD (cross direction) HOM values,
non-woven laminate. The nonwoven laminate of claim 1 , wherein the nonwoven laminate is hydroengorged. The nonwoven laminate of claim 1 wherein the third inner nonwoven layer has a basis weight of at least 10 grams per square meter. The nonwoven laminate of claim 1 , wherein the spun-bond fibers of the first and second outer nonwoven layers comprise polypropylene and at least 5% by weight of a propylene-based elastomer. The nonwoven laminate of claim 1 , wherein the fibers of at least one of the nonwoven layers comprise a slip agent. The nonwoven laminate of claim 1 , wherein the nonwoven laminate comprises a plurality of apertures. forming a first nonwoven web comprising continuous spunbond fibers;
forming a second nonwoven web comprising continuous meltblown fibers;
forming a third nonwoven web comprising continuous spunbond fibers;
thermally bonding the first, second and third nonwoven webs at a pressure of 20 to 60 N/m (Newtons per meter) to form a nonwoven laminate having a regular bond pattern; and
hydrotreating the nonwoven laminate
A method for producing a nonwoven laminate according to claim 1 comprising a. According to claim 7,
The hydraulic processing step includes imparting one or more hole patterns by a plurality of water spraying steps on a corresponding screen each having a predetermined pattern,
The plurality of water injection steps
a first water spray step exposing the laminate to a plurality of water jets at a first pressure range of 80-160 bar;
a second water spray step of exposing the laminate to a plurality of water jets at a second pressure range of 80-160 bar; and
A third water spray step exposing the laminate to a plurality of water jets at a third pressure range of 80-160 bar.
including,
the first water injection step further comprises maintaining a subset of the plurality of water jets at 80 bar;
The method of claim 1, wherein the nonwoven laminate comprises 5% by weight of meltblown fibers. 9. The method of claim 8 wherein the one or more hole patterns comprise at least a first hole formed in the nonwoven web by imparting a first hole pattern and at least a second hole formed in the nonwoven web by imparting a second hole pattern; registered to form in the same location. 10. The method of claim 9, wherein the first and second apertures are of different sizes. 11. The method of claim 10, wherein at least a third hole formed in the nonwoven web by imparting a second hole pattern is formed at a location where there are no holes formed in the nonwoven web by imparting the first hole pattern. delete delete delete delete delete delete delete delete delete delete delete delete delete

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